练习材料：
Lesson 20-1 Snake poison
How it came aboutthat snakes manufactured poison is a mystery. Over the periods their saliva, amild, digestive juice like our own, was converted into a poison that defiesanalysis even today. It was not forced upon them by the survival competition;they could have caught and lived on prey without using poison, just as thethousands of non- poisonous snakes still do. Poison to a snake is merely aluxury; it enables it to get its food with very little effort, no more effortthan one bite. And why only snakes? Cats, for instance, would be greatlyhelped; no running fights with large, fierce rats or tussles with grown rabbits-- just a bite and no more effort needed.
sneɪk ˈpɔɪzn
haʊ ɪt keɪm əˈbaʊt
ðæt sneɪks ˌmænjʊˈfækʧəd ˈpɔɪzn ɪz ə ˈmɪstəri. ˈəʊvə ðə ˈpɪərɪədz ðeə səˈlaɪvə,
ə maɪld, dɪˈʤɛstɪv ʤuːs laɪk ˈaʊər əʊn, wɒz kənˈvɜːtɪd ˈɪntuː ə ˈpɔɪzn ðæt dɪˈfaɪz
əˈnæləsɪs ˈiːvən təˈdeɪ. ɪt wɒz nɒt fɔːst əˈpɒn ðɛm baɪ ðə səˈvaɪvəl ˌkɒmpɪˈtɪʃən;
ðeɪ kʊd hæv kɔːt ænd lɪvd ɒn preɪ wɪˈðaʊt ˈjuːzɪŋ ˈpɔɪzn, ʤʌst æz ðə ˈθaʊzəndz ɒv
nɒn- ˈpɔɪznəs sneɪks stɪl duː. ˈpɔɪzn tuː ə sneɪk ɪz ˈmɪəli ə ˈlʌkʃəri; ɪt ɪˈneɪblz
ɪt tuː gɛt ɪts fuːd wɪð ˈvɛri ˈlɪtl ˈɛfət, nəʊ mɔːr ˈɛfət ðæn wʌn baɪt. ænd waɪ
ˈəʊnli sneɪks? kæts, fɔːr ˈɪnstəns, wʊd biː ˈgreɪtli hɛlpt; nəʊ ˈrʌnɪŋ faɪts wɪð
lɑːʤ, fɪəs ræts ɔː ˈtʌslz wɪð grəʊn ˈræbɪts-- ʤʌst ə baɪt ænd nəʊ mɔːr ˈɛfət ˈniːdɪd.
任务配置：L0 + L4
知识笔记：
单词：1、manufacture：生产，制造，2、saliva：唾液，3、digestive：消化，4、defies：无视，5、analysis：分析，分解，6、prey：猎物，捕食，7、fierce：凶猛的，激烈，8、tussle：争吵，打架，9、
音标：
练习感悟：今天这篇文章，难度适中，读起来还是蛮顺口的。
